Sleep basics
The foundations, in the right order
If you're starting from zero — or you want to make sure you have the fundamentals right — read these six articles in order. Together they cover everything you need to make sense of every other page on this site.
Articles
- 01
How much sleep do adults actually need
Most healthy adults need 7–9 hours. Sleep need is individual, age-dependent, and chronically getting fewer than six hours has measurable consequences.
- 02
What happens to your body during sleep
Sleep is an active biological process. Hormones reset, memory consolidates, the glymphatic system clears waste, and immune cells deploy.
- 03
Sleep stages explained — REM, light, deep
You cycle through stages roughly every 90 minutes. Deep sleep dominates the early night; REM dominates later. Each stage does a different job.
- 04
Circadian rhythm, explained simply
A roughly 24-hour internal clock — set by light, food, and movement — that decides when you feel sleepy or alert.
- 05
What is sleep debt and does it matter
Sleep debt is real and accumulates, but it isn't strictly linear. Here's what the evidence actually shows about catching up.
- 06
Why do we dream
Dreaming serves memory consolidation and emotional processing — the scientific case, separate from the symbolic one.